D-Link DIR-513, Stack Buffer Overflow, CVE-2025-70232 (Critical)

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CVE-2025-70232 is a critical stack-based buffer overflow vulnerability discovered in the D-Link DIR-513 router, specifically in firmware version 1.10. The flaw resides within the web interface’s form handling mechanism. When a request is sent to the `/goform/formSetMACFilter` endpoint, the device processes a parameter named curTime. The underlying code, likely written in C, uses a function like `strcpy` or `sprintf` to copy the value of the `curTime` parameter into a fixed-size buffer located on the stack. The programmer failed to implement proper bounds checking on the length of the user-supplied input. Consequently, an unauthenticated remote attacker can send a malicious HTTP POST request with an excessively long string for the `curTime` parameter. This oversized data overflows the allocated buffer, corrupting adjacent memory on the stack, which contains critical information like the function’s return address. By carefully crafting the overflow payload, an attacker can overwrite this return address and redirect the program’s execution flow to arbitrary shellcode injected within the same request. This grants the attacker the ability to execute malicious code with the full privileges of the device, leading to complete system compromise. The device is end-of-life, meaning no official patch will ever be released by the manufacturer.
Platform: D-Link DIR-513
Version: 1.10 only
Vulnerability: Stack Buffer Overflow
Severity: Critical (9.8)
Date: March 5, 2026

Prediction: No patch ever

What Undercode Say:

Analytics:

  • Vulnerability Type: Classic Stack Buffer Overflow (CWE-121)
  • Attack Vector: Remote (Network)
  • Authentication: Not required
  • Impact: Remote Code Execution (RCE)
  • End-of-Life Status: Product is unsupported, no patch available.

Bash Commands / Exploit Concept:

Proof-of-Concept to test for vulnerability.
Replace <ROUTER_IP> with the target's IP address.
This command sends an overly long 'curTime' value to trigger a crash (DoS).
A full exploit would replace "A"1000 with shellcode and a valid return address.
curl -X POST http://<ROUTER_IP>/goform/formSetMACFilter \
-d "curTime=$(python3 -c 'print(\"A\"1000)')"

Exploit:

1. Target: `/goform/formSetMACFilter` endpoint.

2. Vector: `curTime` POST parameter.

  1. Method: Send approximately 1000 bytes to crash. Precise exploitation requires identifying the exact offset to the return address and crafting ROP chain to bypass modern mitigations like ASLR/DEP if present, though many embedded devices have minimal protection.

Protection from this CVE:

  1. Immediate Replacement: The only 100% effective mitigation is to replace the D-Link DIR-513 router with a supported model.
  2. Isolation: If replacement is impossible, isolate the device on a separate VLAN with no access to the internet or critical internal networks.
  3. Firewall Rules: Block external access to the router’s management interface (ports 80/443) from the WAN side. Restrict LAN access to only trusted administrative IPs.
  4. Monitor Traffic: Monitor for suspicious HTTP POST requests containing excessively long `curTime` parameters to the `/goform/formSetMACFilter` path.

Impact:

  1. Total Device Compromise: Successful exploitation allows an attacker to gain full control over the router.
  2. Network Pivot: The compromised router can be used as a foothold to launch attacks against other devices on the internal network.
  3. Data Theft: Attackers can monitor and capture all network traffic passing through the router, including unencrypted credentials.
  4. Botnet Recruitment: The device can be enslaved into a botnet for use in DDoS attacks or other malicious activities.
  5. Permanent Denial of Service: A simpler, non-optimized overflow can permanently crash the device, requiring a physical power cycle to recover, or even brick it permanently.

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Sources:

Reported By: nvd.nist.gov
Extra Source Hub:
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